Disparate movement behavior and feeding ecology in sympatric ecotypes of Atlantic cod

Coexistence of ecotypes, genetically divergent population units, is a widespread phenomenon, potentially affecting ecosystem functioning and local food web stability. In coastal Skagerrak, Atlantic cod (Gadus morhua) occur as two such coexisting ecotypes. We applied combination acoustic telemetry, genotyping, stable isotope analysis to 72 individuals investigate movement ecology niche putative “Fjord” oceanic “North Sea” ecotypes—thus named based on previous molecular studies. Genotyping individual origin assignment suggested 41 were Fjord 31 North Sea Both ecotypes found throughout the fjord. Seven percent ecotype left study system during while 42% left, homing natal spawning grounds. Home range sizes similar for but highly variable among individuals. had significantly higher ?13C ?15N values than cod, suggesting they exploited different niches. The results suggest may possess innate differences in feeding ecologies thus fill functional roles marine ecosystems. This highlights importance conserving interconnected populations ensure structures.